High pressure fuel injection unit

ABSTRACT

An accumulator type of fuel injection nozzle having an injection valve, a first electromagnet for initiating fuel injection, and a second electromagnet for controlling the lift amount of the injection valve is provided with an energizing arrangement which enables effective fuel injection control but which greatly reduces the risk of burning damage to the electromagnets. The amp-turn characteristics of the first electromagnet coil provide for a rapid start-up time wherein the peak magnetic flux is reached relatively quickly. In contrast, the amp-turn characteristics of the second electromagnet coil provide for a more gradual start-up time so that peak magnetic flux is reached more gradually. The second electromagnet coil is also adapted to achieve a relatively large magnetic flux without the need for large current supply. In operation, when the second electromagnet is energized, such energization is started before energization of the first electromagnet for a particular fuel injection cycle.

BACKGROUND OF THE INVENTION

This invention relates to a high pressure fuel injection unit for anengine, and more particularly to an improved arrangement for energizingthe electromagnetic assemblies of the injection unit which control fuelinjection timing and the lift of the injection valve respectively so asto reduce the risk of burning damage to the electromagnetic assembliesand to improve the durability of the injection unit.

One popular form of fuel injection unit for engines is the so-called"accumulator type." This type of injection nozzle includes anaccumulator chamber that is charged with fuel under pressure and whichcommunicates with a nozzle port. An injection valve is supported withinthe accumulator chamber and controls the discharge through the nozzleport. An actuating device is associated with the injection valve and ismoveable within a control chamber that is also pressurized with fuel. Avalve is associated with the control chamber and is opened so as toreduce the pressure and cause the pressure in the accumulator chamber tounseat the injection valve and initiate fuel injection. Typically, thevalve is operated by a main electromagnetic assembly that is containedwithin the housing of the fuel injection nozzle.

To control the amount of fuel injected, the inventors have proposed toprovide an additional and separate subelectromagnetic assembly withinthe accumulator chamber to control the lift movement of the injectionvalve. This assembly is provided with a coil which, when energized,attracts a lift regulating member downward against a holder member whichsupports the coil to permit only a relatively small upward lift movementof the injection valve to allow injection of a smaller amount of fuelwhen injection is initiated. On the other hand, when the coil is notenergized, the regulating member moves freely within a bore of theholder member so the injection valve is able to move upward a greaterdistance to permit injection of a larger amount of fuel.

Although previous injection units of this type have been generallysatisfactory, effective operation of such units has typically requiredthat regulating member be held down against the holding member with amagnetic flux which is greater than the magnetic flux generated by themain electromagnet during the entire time of small lift operation.Generation of such a large magnetic flux in the sub-electromagnetic coilhas typically required that the coil be supplied with a relatively largecurrent during the entire small lift operation. This may cause burningdamage to the coil and may also decrease the durability of the coil.

It is, therefore, a principal object of this invention to provide animproved energizing arrangement for an electromagnetic assembly whichcontrols the lift amount of an injection valve so as to eliminate orgreatly decrease the likelihood of causing burning damage to theelectromagnetic assembly.

It is another object of this invention to provide an improved energizingarrangement for an electromagnetic assembly which controls fuelinjection, wherein this electromagnetic assembly does not require alarge current for a long period of time during injection process so asto eliminate or greatly decrease the likelihood of causing burningdamage to the electromagnetic assembly.

SUMMARY OF THE INVENTION

This invention is adapted to be embodied in an accumulator type ofinjection nozzle that is comprised of an outer housing assembly defininga cavity partitioned into an accumulator chamber which is adapted to besupplied with high pressure fuel and a coil chamber. A nozzle port leadsfrom the accumulator chamber and an injection valve is moveable betweena closed position and an open position for controlling the discharge offuel from the accumulator chamber through the nozzle port. A controlchamber is also incorporated that receives pressurized fuel. Anactuating member is supported for movement within this control chamberand is associated with the injection valve for retaining the injectionvalve in its closed position when the control chamber is pressurized andfor movement of the injection valve to its open position when pressureis relieved in the control chamber. A valve means is moveable between aclosed position for maintaining pressure in the control chamber and anopen position for relieving pressure in the control chamber foreffecting fuel discharge through the nozzle port.

In accordance with the invention, a first electromagnet is positionedwithin the outer housing assembly for moving the valve means to one ofthe positions when the first electromagnet is energized. A secondelectromagnet is also positioned within the outer housing assembly forcontrolling the lift amount of the injection valve when the secondelectromagnet is selectively energized or de-energized. In accordancewith the invention, when the second electromagnet is energized,energization thereof is started before energization of the firstelectromagnet for a given fuel injection cycle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional front view of a fuel injection nozzleconstructed in accordance with an embodiment of the invention.

FIG. 2 is a cross-sectional side view of the fuel injection nozzle.

FIG. 3 is an enlarged cross-sectional view of the control chamberportion of the fuel injection nozzle.

FIG. 4 (a) is a bottom view of the shim plate of the fuel injectionnozzle.

FIG. 4(b) is a cross-sectional view taken alnog line IV(b)--IV(b) ofFIG. 4(a).

FIG. 5 is an enlarged cross-sectional view showing the armature portionof the regulating member.

FIG. 6(a) is a side view of the stopper plate for the regulating member.

FIG. 6(b) is a bottom view of the stopper plate.

FIGS. 7(a) through (i) are wave form diagrams illustrating the operationof the fuel injection nozzle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

Referring to the drawings, and in particular to FIGS. 1 and 2, a fuelinjection nozzle constructed in accordance with an embodiment of theinvention is identified generally by the reference numeral 11. Theinjection nozzle 11 is comprised of an outer housing assembly, indicatedgenerally by the reference numeral 12, that is adapted to be mounted, ina manner to be described, in the cylinder head of an internal combustionengine with a nozzle port 13 communicating with the combustion chamberfor delivering fuel to it in a manner to be described. The invention maybe used for direct cylinder injection, or instead may be utilized inconjunction with manifold injection systems. The invention, however, hasparticular utility with direct fuel injection, for example, as used withhigh speed diesel engines.

Fuel is supplied to the injection nozzle 11 from a remotely positionedfuel tank (not shown) by means of a high pressure pump (not shown).Excess fuel is returned back to the fuel tank or reservoir through areturn line.

The outer housing assembly 12 is comprised of a casing body 14 and acover member 15 which is removably seated within an opening 16 at thetop of the casing body 14. The casing body 14 has a threaded lower end17 which is adapted to be threaded into a suitable aperture in thecylinder head of the associated engine (not shown) in a known manner.The nozzle port 13 is defined by a tip 18 that has a threaded portionwhich is received in a threaded bore 19 formed at the lower end of thecasing body 14. An adjusting shim 21 is interposed between the nozzlepiece 18 and the lower end of the casing body 14 for length adjustmentof the fuel injection nozzle 11.

An injection valve 22 is slidably supported within a bore 23 of thenozzle piece 18 and has a guide portion 24 formed with a helical grooveat its lower portion, and a flow controlling tip 25 which, when in theclosed position, closes the injection nozzle port 13.

An accumulator chamber 26 is formed at the upper end of and above thebore 23 in the lower portion of the casing piece 14. The accumulatorchamber 26 is closed at its upper end by means of a partitioning plate27 that is held against a shoulder 28 in the casing body 14 by abottomed cylindrical pipe portion 29 of the cover member 15. A cap 31having a threaded bore engages a threaded portion of the upper portionof the casing body 14 and presses against a top plate 32 of the covermember 15 to hold it in position.

The cover member 15 is formed with an inlet conduit 33 that has athreaded external portion 34 so as to receive a fitting 35 forconnecting a supply line 36 extending from the pressure pump to theinlet conduit 33. The inlet conduit 33, which is generally a drilledopening, extends axially along the cover member 15 at its periphery atone side thereof and communicates at its lower end with the accumulatorchamber 26 through a corresponding fuel groove 37 formed in thepartitioning plate 27 and groove 39 in spacer 40 for delivering fuel tothe accumulator chamber 26.

The partitioning plate 27 is generally disc-shaped, and serves toseparate the accumulator chamber 26 from a coil chamber 38 in the upperportion of the casing body 14. The partitioning plate 27 has a centrallypositioned aperture 41 into which an actuator portion 42 of the injectorvalve 22 is slidably supported and which closes a control chamber 43formed within the partitioning plate 27 in a space defined by the upperportion of this aperture 41 and an inner face 44 of the partitioningplate 27, as shown in FIG. 3. A shim plate 45 is positioned between atop face 46 of the actuator portion 42 and the partitioning plate face44 as shown in FIG. 3 for adjusting the lift of the injection valve 22.

The shim plate 45 is an annular plate, as shown in FIGS. 4(a) and 4(b),and has raised portions 47 projected every 90 degrees which abut againstthe partitioning plate face 44. Grooved portions 48 are interposed inbetween for receiving pressurized fluid. This shim plate 45 may beinstalled upside down.

A restricted orifice 49 communicates the control chamber 43 with thecoil chamber 38. As shown in FIG. 3, a throttle hole 51 fixed in the endof the actuator portion 42 and an axial passage 52 formed through theupper portion of the injection valve 22 communicate the control chamber43 with the accumulator chamber 26. The control chamber 43 communicateswith the throttle hole 51 to receive the pressurized fluid and normallyurge the injection valve 22 toward its downward or closed position.

A coil compression spring 53 encircles the injection valve 22, and atits lower end engages a cup-shaped retainer 54 that is held axially inposition against the helical groove of the guide portion 24. The upperend of the spring 53 bears against an upper spring seat 55 which ispositioned against a shoulder formed by an enlarged portion 56 at thelower end of a bore 57 formed in a holder member 58. The coilcompression spring 53 acts to further assist in maintaining theinjection valve 22 in the closed position, as shown in FIGS. 1 and 2.

A valve 59 is supported at the upper end of the partitioning plate 27and controls the opening of the restricted orifice 49. The valve 59comprises a headed portion 61 that is received within a correspondingrecess formed in an enlarged disc-like armature plate 62, and a stemportion 63 which is in engagement with a spring 64 so as to bias thevalve 59 toward its closed position to maintain the orifice 49 in itsclosed position.

The valve 59 is opened and closed so as to control the discharge of fuelfrom the nozzle port 13 by means of an electromagnetic assembly,indicated generally by the reference numeral 65. This electromagneticassembly 65 includes a generally cylindrical yoke 66 that has a threadedopening at an enlarged diameter lower end portion which is received on athreaded portion of the partitioning plate 27 so as to secure theelectromagnetic assembly 65 in position. The electromagnetic assembly 65is further comprised of a solenoid coil or winding 67 that is disposedwithin the housing or yoke 66 and which encircles an armature 68. Thearmature 68 is formed with a bore that slidably supports the valve stem63 of the valve 59.

A circuit (not shown) is used for energizing the coil 67 of theelectromagnetic assembly 65 for opening and closing the valve 59.

The condition shown in FIGS. 1 and 2 is that which occurs when thewinding 67 is de-energized. When the winding 67 is deenergized, thevalve 59 will be held in its closed position by the spring 64 so thatthe accumulator chamber 26 and control chamber 43 may be pressurized.

At the appropriate instant for fuel injection to begin, which may becontrolled by any suitable strategy, the winding 67 is energized. Whenthis happens, the valve armature 62 will be attracted upwardly by theflux in the armature 68 so as to urge the stem portion 63 upwardly andopen the valve 59 against the action of the spring 64. This will openthe orifice 49 to rapidly deplete the pressure in the control chamber43. The higher pressure of the fuel acting in the accumulator chamber 26will then urge the injection valve 22 upwardly to its open position andpermit fuel to issue from the nozzle port 13. When the fuel pressure inthe accumulator 26 has been depleted, the spring 64 will move theinjection valve 22 to its closed position and the fuel pressure can thenbuild up in the accumulator chamber 26. This action is initiated bydiscontinuing the energization of the winding 67 so as to close thevalve 59 and permit pressure in the control chamber 43 to again buildup.

The amount of fuel injected can be varied by varying the lift distanceof the injection valve 22 by energizing or deenergizing a coil 72 of asub-electromagnetic assembly, indicated generally by the referencenumeral 71, and which is positioned within the accumulator chamber 26for adjusting the lift and/or for detecting the lift of the injectionvalve 22. The coil 72 is supported within the holder member 58. Aregulating member 73 comprised of an armature 74 fixed on the upper endof a cylindrical guide portion 75 which is slidably supported within thebore 57 of the holder member 58 regulates the lift amount of theinjection valve 22. The lower end of the cylindrical guide portion 75 ispositioned above a stopper portion 76 of the injection valve 22 todefine a smaller lift distance of the injection valve 22. A stopperplate 78 made of non-magnetic material is positioned above the armature74 and has a contacting face 79 in contact with the lower end of thepartitioning plate 27 so as to provide a stop surface for the regulatingmember 73 and to prevent transmission of stray magnetic flux pathsthrough the partitioning plate 27. The contacting face 79 has radiallyextending grooves 80 for receiving pressurized fluid. A stopper plate 78having a different thickness may be substituted to adjust the maximumlift of the regulating member 73 and thus the lift of the injectionvalve 22.

If injection of a larger amount of fuel is desired, the coil 72 ismaintained in a de-energized state so as to allow the regulating member73 to move freely between the top surface of the holder member 58 andthe stopper plate 78. In this condition, the injection valve 22 will beurged upward the distance defined by the space between the top face ofthe shim plate 45 and the partitioning plate face 44. On the other hand,if injection of a smaller amount of fuel is desired, the coil 72 isenergized. When this occurs, the armature 74 is attracted downwardly bythe flux in holder member 58 so as to lower the cylindrical guideportion 75. In this state, the injection valve 22 will be moved upwardthe distance defined by the space between the lower end face of theguide portion 75 and the upper face of the injection valve stopperportion 76 so as to permit a smaller amount of fuel to issue from thenozzle port 13.

With this type of arrangement, the amount of fuel delivered to thecombustion chamber during each cycle of operation can be controlled aswell as the injection pattern so as to provide optimum fuel delivery andcontrol.

In accordance with the invention, the wire of coil 67 has a largerdiameter than the wire of coil 72 of the subelectromagnetic assembly 71,and coil 67 is also wound by a lesser number of turns. The coil 67 isalso designed and operated so that, for a given voltage and resistanceand inductance characteristics, the current in amperes (A) supplied toit is greater than its number of turns (T); that is, the amp-turncharacteristics of coil 67 are given by the relationship: A is greaterthan T. With these characteristics, the peak magnetic flux produced bythe coil 67 is reached very quickly when a relatively large current issupplied to the coil 67, thus giving the coil 67 relatively quickstart-up characteristics.

On the other hand, the wire of coil 72 has a smaller diameter and coil72 is wound by a greater number of turns. The design and operationalcharacteristics of this coil 72 are such that, for a given voltage andresistance and inductance characteristics, the current in amperes (A)supplied to it is less than its number of turns (T); that is, theamp-turn characteristics of coil 72 is such that A is less than T.Hence, the resulting peak magnetic flux generated by coil 72 is reachedmore gradually, giving the coil 72 slower start-up characteristics.

In addition, the holder member 58 has a stepped portion 58a projected uparound its axis which serves to form a gap, designated by A in FIG. 5,which functions as a magnetic circuit interrupting portion for abruptlyreducing the magnetic flux applied to the armature 74 when the electriccurrent being supplied to coil 72 is interrupted.

With this type of arrangement, the amount of fuel injected can be variedby changing the lift distance of the injection valve 22 between asmaller lift indicated by (1) in FIG. 7(i) and a larger lift indicatedby (L) in FIG. 7(i) while substantially reducing the risk of either ofthe coils 67 or 72 suffering burn damage.

When injection of a smaller amount of fuel and hence the smaller liftdistance (1) for the injection valve 22 is desired, a control signal isfirst transmitted to the electromagnetic assembly 71, as shown in FIG.7(e), which causes a driving current to be supplied to coil 72 causing amagnetic flux to be generated by coil 72, as illustrated in FIGS. 7(f)and 7(g) respectively. When the magnetic flux in coil 72 reaches apredetermined magnitude, the armature 74 is attracted onto the holdermember 58, as graphically shown in FIG. 7(h). Because the amp-turncharacteristics of coil 72 are given by the relationship: A<T, thestart-up characteristics of coil 72 is more gradual, as illustrated inFIGS. 7(g). Once peak magnetic flux is reached in coil 72 and movementof the regulating member 73 is completed, the coil 67 is energized toinitiate fuel injection. This timing may vary depending on thecharacteristics of the coils 67 and 72; however, coil 67 should not beenergized until movement of member 73 is completed.

After peak magnetic flux is applied to the regulating member 73 by coil72 so as to complete movement of the regulating member 73, a controlsignal is transmitted to the electromagnetic assembly 65, as shown inFIG. 7(a), which initially causes a relatively large driving current tobe supplied to coil 67 whereby peak magnetic flux in the coil 67 isgenerated very rapidly, as shown in FIGS. 7(b) and 7(c) respectively.This causes a rapid upward movement of valve armature 62 and stem 63which, in turn, causes upward movement of the injection valve 22 untilthe stopper portion 76 engages the lower end face of the guide portion75. Once the valve 59 is completely lifted and fuel injection occurs,the driving current for coil 67 is immediately decreased, as shown inFIG. 7(b), which results in a corresponding decrease in the peakmagnetic flux generated by the coil 67.

When a larger amount of fuel and therefore a large lift distance (L) forthe injection valve 22 is desired following a smaller injection, thecontrol signal to the sub-electromagnetic assembly 71 is greatlyreduced, as shown in FIG. 7(e), so as to abruptly interrupt the drivingcurrent being supplied to coil 72 (FIG. 7(f)), causing gradual reductionof its peak magnetic flux (FIG. 7(g)). This reduces the attracting forceapplied to the regulating member 73 so that the injection valve 22 maybe lifted up the distance L, pushing up the regulating member 73 in theprocess, as illustrated in FIG. 7(i).

After this larger amount of fuel is injected, the control signal to theelectromagnetic assembly 65 drops as illustrated in FIG. 7(a). Themagnetic flux of coil 67 is then reduced through interruption of itsdriving current (FIGS. 7(c) and 7(b)), thereby causing the valve 59 toclose the orifice 49 by action of the spring 64 which, in turn, causesthe pressure in the control chamber 43 to again build up.

By employing a lift coil 72 which has slower start-up characteristicsbut which is able to achieve a relatively large magnetic flux during thesmall injection process without the need for a large current, and byutilizing an arrangement wherein energization of coil 72 occurs beforeenergization of coil 67 so as to complete movement of the regulatingmember 73 before injection is initiated, the chance that coil 72 will bedamaged by burning is greatly reduced. This also improves the durabilityof the electromagnetic assembly 71.

Moreover, the gap A created between the holder member 58 and thearmature 74 permits the magnetic force applied to the regulating member73 to be abruptly eliminated when the electric current supplied to thecoil 72 is interrupted. As a result, the regulating member 73 is freedonce the electric current is interrupted so that the lift distance ofthe injection valve 22 can be rapidly changed. This permits greatercontrol accuracy of the injection process.

Referring again to FIGS. 1 and 2, a feeder wire structure is providedfor energizing the coil 72 of the sub-electromagnetic assembly 71 so asto vary the lift distance of the injection valve 22, as desired. Thisstructure includes a pair of bores 81 which extend axially through thecap 31 and cover member 15 in the periphery thereof to provide a wirepassage for feeder wires to the coil 72. The feeder wires are defined bya pair of terminal feeder rods 82, preferably made of copper, whichextend through the bores 81 with insulating sleeves 83 being interposedbetween holding portions 84 of the bores 81 and larger diameter portions85 of the feeder rods 82. The larger diameter portions 85 of the feederrods 82 are fixed to the inner surface of the insulating sleeves 83 witha high strength adhesive to withstand the high fuel pressure within theinjection nozzle 11. A soft sealing adhesive 87 is interposed between asmaller diameter portion 88 of each feeder rod 82 and a sealing portion89 of the bores 81. This sealing adhesive 87 is longitudinallycompressed by the fuel pressure within the accumulator chamber 26 whichacts on the lower end of the adhesive 87 causing it to radially expandso as to provide a strong seal around the smaller diameter portion 88 ofeach feeder rod 82 within the coil chamber 38. A nut 86 is affixed onthe posts 90 of each rod 82 so as to afford attachment to an appropriatelead wire (not shown).

The lower ends of the smaller diameter portions 88 extend throughcircumferential grooves 91 in the partitioning plate 27 and arepositioned in proximity to guide holes 92 in the spacer 40. A pair ofwire harnesses 94 are connected to the coil 72 and extend downwardlythrough guide holes 95, and then upwardly through guide grooves 96 and97, where the wires 94 are soldered to the lower ends of the smallerdiameter portions 88.

With this type of feeder wire structure, the wire passages 81 can besealed along their entire length to insure a sufficient seal against thehigh pressure which forms within the fuel injection nozzle 11, withoutthe need for increasing the outer diameter of the injection nozzle 11.The seal is particularly effective when the wire passages 81 is formedin the cover member 15 or like structure which is originally formedthicker to accommodate the inlet conduit 33. This construction alsoeliminates the need for increasing the outer diameter of the injectionnozzle 11. It should be noted that, although the wire passages 81 areformed through the cover member 15 in the preferred embodiment, thesewire passages 81 may instead be formed through another structure inwhich the inlet conduit 33 is formed, for example, through the casingbody 14 when the inlet conduit 33 is formed therein.

This type of feeder wire structure also provides for easy installationof the injection nozzle into the engine and permits the injection nozzle11 to be oriented in any number of different positions within the enginewithout interference from the engine or other components.

Moreover, the cylindrical pipe portion 29 of the cover member 15 has apair of knock pin holes 101 formed in the lower portion. Knock pins 102are fitted into these pin holes 101 and extend downwardly through knockpin grooves 103, 104 and 105 formed through the periphery of thepartitioning plate 27, the spacer 40 and the holder member 58respectively, and are fitted into oppositely oriented knock pin holes106 formed in the shoulder 28. These knock pins 102 serve to preventthese components from rotating relative to each other, and thus toprevent the feeder wire structure from becoming displaced.

It should be readily apparent from the foregoing description that thedescribed fuel injection nozzle is constructed and arranged so as toimprove its durability. The injection nozzle described herein isparticularly adapted for supplying varying amounts of fuel to the enginewhile reducing the probability of coil burn damage occurring. It is tobe understood, however, that the foregoing description is only that of apreferred embodiment of the invention, and that various changes andmodifications may be made without departing from the spirit and scope ofthe invention, as defined by the appended claims.

We claim:
 1. An accumulator type of injection nozzle comprising an outerhousing assembly defining a cavity partitioned into an accumulatorchamber adapted to be supplied with high pressure fuel and a coilchamber, a nozzle port leading from said accumulator chamber, aninjection valve moveable between a closed position and an open positionfor controlling the discharge of fuel from said accumulator chamberthrough said nozzle port, a control chamber for receiving pressurizedfuel, an actuating member supported for movement within said controlchamber and associated with said injection valve for retaining saidinjection valve in its closed position when said control chamber ispressurized and for movement of said injection valve to its openposition when pressure is relieved in said control chamber, valve meansmoveable between a closed position for maintaining pressure in saidcontrol chamber and an open position for relieving pressure in saidcontrol chamber for effecting fuel discharge through said nozzle port, afirst electromagnet within said outer housing assembly for moving saidvalve means to one of said positions when said first electromagnet isenergized, and a second electromagnet within said outer housing assemblyfor controlling the lift amount of said injection valve by selectivelyenergizing or de-energizing said second electromagnet, .Iadd.whereinsaid first and second electromagnets have first and second coilsrespectively, said first coil being wound with a lesser number of turnsthan said second coil and the wire of said first coil having a largerdiameter than the wire of said second coil and .Iaddend.wherein whensaid second electromagnet is energized, energization of said secondelectromagnet is started before energization of said first electromagnetfor a given fuel injection cycle. .[.2. An accumulator type of injectionnozzle as recited in claim 1, wherein said first and secondelectromagnets have first and second coils respectively, the wire ofsaid first coil having a larger diameter than the wire of said secondcoil and said first coil is wound with a lesser number of turns thansaid second coil..].
 3. An accumulator type of injection nozzle asrecited in claim .[.2.]..Iadd.1.Iaddend., wherein the amp-turncharacteristics of said first coil is such that the current supplied tosaid first coil is greater than its number of turns so that, whenenergized, said first coil reaches peak magnetic flux more quickly thansaid second coil when said second coil is energized.
 4. An accumulatortype of injection nozzle as recited in claim 3, wherein the amp-turncharacteristics of said second coil is such that the current supplied tosaid second coil is less than its number of turns.
 5. An accumulatortype of injection nozzle as recited in .[.2.]. .Iadd.1.Iaddend., whereinthe amp-turn characteristics of said second coil is such that thecurrent supplied to said second coil is less than its number of turns sothat, when energized, said second coil reaches peak magnetic flux lessquickly than said first coil when said first coil is energized.
 6. Anaccumulator type of injection nozzle as recited in claim 1, furthercomprising a regulating member moveable by said second electromagnetwhen energized such that when said second electromagnet is energized,movement of said regulating member is completed before energization ofsaid first electromagnet for a given fuel injection cycle. . Anaccumulator type of injection nozzle as recited in claim 1, wherein saidfirst electromagnet is within said coil chamber and said secondelectromagnet is within said accumulator chamber. .Iadd.8. Anaccumulator type of injection nozzle as recited in claim 1, furthercomprising a holder member having an upper surface and a bore formedtherein, and a regulating member movable by said second electromagnetand comprised of a guide portion having upper and lower ends andslidably supported within the bore and an armature having a lowersurface facing the upper surface of said holder member and fixed on theupper end of the guide portion, wherein when electric current issupplied to said second coil, the upper surface of said holder memberand the lower surface of said armature each have a portion in contactwith each other and each have another portion apart from each other..Iaddend.